1. Field of the Invention
The present general inventive concept relates to a print medium supplying device and an image forming apparatus having the same, and more particularly, to a print medium supplying device and an image forming apparatus to reduce a falling impact of a mounting plate on which a print medium is mounted when the print medium supplying device is in a mounting position and is separated from the image forming apparatus.
2. Description of the Related Art
In general, a print medium supplying device is employed in an image forming apparatus such as a printer, a copy machine, a facsimile, etc., and picks up a print medium mounted inside thereof, one by one, to be supplied to the image forming apparatus. The print medium supplying device may be classified according to a print medium mounting capacity such as a print medium supplying device having the print medium mounting capacity within several hundred sheets of print media, and a print medium supplying device of high capacity having the print medium mounting capacity of approximate 2,000 sheets of print media.
Referring to FIG. 1, a related art print medium supplying device includes a frame 11 accommodating a print medium 1 therein, and a mounting plate 13 disposed within the frame 11 to move upward and downward. The print medium 1 is mounted on the mounting plate 13. The mounting plate 13 is driven by a driving force supplied from a driving source (not illustrated) provided in an image forming apparatus, and an elevating unit 15. The elevating unit 15 includes first and second pulleys 16 and 17 distantly disposed in a vertical direction of the frame 11, and a timing belt 19 to wind around the first and second pulleys 16 and 17. The first pulley 16 receives the driving force supplied from the driving source through a shaft 16a and a coupler (not illustrated) provided on a same axis to rotate the timing belt 19. The mounting plate 13 is disposed proximate to the timing belt 19 to move upward and downward depending on a driving direction of the timing belt 19. Accordingly, the print medium 1 can be smoothly supplied by adjusting a height of the mounting plate 13 according to a number of the print media 1 mounted on the mounting plate 13.
If the print medium supplying device is detached from the image forming apparatus to additionally mount the print medium 1, the coupler is separated so that the driving force transmitted from the driving source to the shaft 16a can be intercepted. Accordingly, the first and second pulleys 16 and 17 rotate free, and the mounting plate 13 falls free by its own weight. Accordingly, the print medium supplying device may be damaged, and noises may be generated.
The related art print medium supplying device further includes a gear 21 provided coaxially with the first pulley 16, and a gear oil damper 23 engaged to the gear 21 to prevent the mounting plate 13 from falling free. Accordingly, when the coupler is separated, the mounting plate 13 falls down while the first pulley 16 rotates in a low speed, thereby relieving the problem related to the free falling of the mounting plate 13.
However, in the related art print medium supplying device as illustrated in FIG. 1, since the weight on the mounting plate 13 and a height of a central point of the weight thereon vary according to a number of the print media 1 mounted on the mounting plate 13, it is difficult to design the gear oil damper 23 to be appropriate for such various conditions.
Accordingly, the gear oil damper 23 is designed based on a condition that there is no print medium 1 mounted on the mounting plate 13.
However, if the gear oil damper 23 is designed under this condition, a buffering action corresponding to the gear oil damper 23 is weakened. Accordingly, if the print medium supplying device is detached from the image forming apparatus while a considerable number of print media 1 are mounted on the mounting plate 13, the print medium supplying device may be damaged, and noises may be generated.